Both wheelchair and invalid chairs have been constructed which include tray or writing desk assemblies. Many of the trays which have been provided on invalid chairs, however, are two bulky for mounting to and use on a wheelchair. Accordingly, wheelchair-mounted trays tend either to be undesirably small or so bulky that they must be removed and stored apart from the chair, often by an attendant.
U.S. Pat. Nos. 3,870,362; 3,860,285; 3,788,695; 3,580,631; 3,575,466 and 3,123,397 are examples of relatively bulky trays or desk assemblies that are designed primarily for use with invalid chairs. Such invalid chairs are normally propelled by an attendant and do not have large drive wheels, as would be conventionally found in a wheelchair. Accordingly, many of the structures disclosed in these patents employ large tray assemblies which are movable to a stored position at the side of the invalid chair. While adequate for invalid chairs, these tray and desk assemblies would conflict or interfere with the drive wheels present on conventional wheelchairs.
U.S. Pat. Nos. 3,547,488; 2,799,324 and 1,217,231 disclose desk tops or trays which are mounted to highchairs, classroom chairs and the like. Again, the absence of any drive wheel structure from the chair to which the desk or tray is mounted has produced structures in which the desk top is merely supported from a side of the chair when in the stored position. These structures, therefore, tend to be adequate for the chairs to which they are mounted, but inadequate for use with a wheelchair. U.S. Pat. No. 3,999,798 is typical of a tray assembly that is mounted to a wheelchair and is foldable to a compact stored position along the side of the chair. In order to enable storing directly on the chair, the tray of U.S. Pat. No. 3,999,798 is relatively small, enabling the same to be stored in a location which is almost entirely in advance of the wheelchair drive wheels.
Trays or desk top structures which are designed to be attached to the wheelchair arm structure in a manner similar to the tray on a baby's highchair have the further negative psychological impact on the user of suggesting that the disabled person is as helpless as an infant. This is coupled with the inherent awkwardness of such removable trays and the likelihood that they will often not be available when they are needed.